Impact tool



R. H. POTT IMPACT TOOL July 28, 1936.

Filed Oct. 6, 1952 2 Sheets-Sheet l IMPACT TOOL Filed Oct. 6, 1952 2 Sheets-Sheet 2 liiatented July 28, 1936 'UNITED STATES PATENT OFFICE 22 Claims.

'I'he invention relates generally to impact tools and more particularly to tools of this character for applying a torsional force.

An object of the invention is to provide a simple tool embodying a new and improved means for producing a rapid succession of impacts of great force.

A further object of the invention resides in the provision 'of an impact tool for imparting torsional force to a part engaged by the tool which embodies novel means for increasing the force of the impact over the force delivered directly by a driving member.

More specifically stated, an object is to provide, -in a tool of this character, means for momentarily accumulating or storing up energy supplied by a constantly driven power source to be expended periodically in moving the hammer part of the tool rapidly and with a sudden im pact against the driven part or tool head.

Another object is to provide a tool of this character having a normally inactive hammer adapted tov be automatically connected with a constantly driven power source as an incident to the application of the tool to the work.

Another object is to provide such a tool adapted by a series of impacts to apply torsional force in either direction.

Another object is to provide a novel power accumulator for such a tool capable of delivering substantial impacts in rapid succession.

Other objects and advantages will become apparent in the following description and from the accompanying drawings, in which:

Figure 1 is a longitudinal central sectional view of a tool embodying the features of the invention.

Fig. 2 is an enlarged fragmental portion of Fig. 1 -showing other portions of the tool in cross section.

Fig. 3 is a side elevational view of the power accumulator in its 'normal form.

Fig. 4 is a cross lsectional view of the accumulator taken along the line 4-4 of Fig. 3.

Fig. 5 is a fragmental portion of Fig. 2 showing the power accumulator in its twisted relation.

Fig. 6 is a sectional view taken along the line 6 6 of Fig. 5. Y

Fig. 7 is a perspective view showing the power accumulator and the associated parts of the drive in an axially separated alined relation generally similar to their relationship in the assembled tool.

While the invention is susceptible of various modifications and alternative constructions, I

have shown in the drawings and will herein describe in detail the preferred embodiment, but it (cisl- 54) is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the appended claims.

In the form illustrated the invention is embodied in a portable tool comprising a motor housing I0 adapted to be supported by opposed radial handles II, and carrying at one end of the housing an elongated extension or casing I2 at 10 the remote end of which a rotatable driven element or head I3 is located for operative engagement with the Work.

The motor (not shown) mounted within the housing I0 is preferably reversible in a conven- 15 tional manner and may be of any preferred type, as, for example. an electric or pneumatic motor, with its rotor shaft I4 inconstant driving relation to a speed reduction gearing I5. The gearing I5 is disposed within a gear box I6 inter- 2O lposed between the housing I0 and the extending casing I2, the gear box I6 being secured to the housing I0 by bolts I1, while bolts I8 serve to fix the casing I2 to the gear box.

The reduction gearing I5 terminates in a gear 25 I 9 flxed on a shaft 20 which projects from the gear box I6 axially into the casing I2 and constitutes the constantly driven element of a driving connection housed within the casing I2 and through which the head I3 is actuated. This 30 driving connection includes a hollow cylindrically shaped impact element or hammer 2| mounted for rotation about the axis of the casing and driven from the shaft 20. The driving connection between the shaft 20 and the hammer 2| 35 comprises a iiexible device and power accumulator 22 preferably mounted within the hammer 2| and capable of accumulating or storing up energy supplied by the shaft 20 for intermittently moving the hammer 2| rapidly and with a great 40 impact against a part of the head I3 to .rotate the same.

The head I3, as shown in Fig. 1, is mounted for rotation about the axis of the casing l I2 in a bearing sleeve 23 projecting from an end wall 24 45 which is screw-threadedrinto the end of the casing I2. Between the inner end of the head I3 and the hammer 2| an impact clutch 25 ispro vided comprising clutch elements or teeth 26 and 21 formed respectively on the head I3 and the 50 hammer 2|. The clutch elements 26 and 2l have sloping cam shoulders or faces 28 on each side surface thereof as shown in Fig. 1, and so that resistance of the head I3 to turning tends to cause a conjoint camming action of these shoul- 55 trai shaftzsupoxrwnicjnfirisfmounted for-.relative rotativeand-liigitudinalmovement When rotation l of.v 'the head I3 `is resisted by predetermined force',V (the continued rotation of the shaft 20 causesftwisting of "the accumulator 22, as shown in"F.?ig.- of the drawings, 'and asan. Incident to the twisting a simultaneous and prol portional shortening of the `accumulator so that Y vthe shoulders .23 cam" out of engagement.

hammer is shifted longitudinallyfby lthe device:`

fUpo'nseparation of l.the clutch-teethf.26 .an'd 2 the hammer 2| is free to'berotated through 180 by the accumulator 22,-during `which rotation the i' 22 so.' as to again engage the opposed faces 28. of

clutch teeth with a 'substantial vrotative impact.

' 'I'he extent of such free-rotation off'the hammer is of; course determined Vby the number and forni of the clutch teeth 26 and 21, two diametrically opposite pairs of these teeth being provided inf the present too1.*'The-clutch teeth 26.and 21 are preferably relativelyy narrowvin a circumfer-f entialdirection as shown in Fig.v 6 and are spaced 180. from each other, thereby providing relatively large spaces 30 between the teeth; Thus the return longitudinal movement, ofthe hammer f 2l and its clutch teethv21 toward engaging relation tothe teeth 26 may commence in the initial portion 'of the free rotative movement of the' hammer, regardless of the direction of such rota,-

'tion. whereby to insure completion of suchreturn movement vand anv effective torque-transmitting engagement of the clutch elements. e

In mounting the hammer 2l on the Acentral shaft'29 an end wall 3l is provided on ,the hammer adjacent to the head I3 so Aas to carry the clutch elements 21 and define a central bearing opening `Asliding'ly and rotatably vengaging the shaft 29.

At the other end of the hammer 2l an end wall 3la is removably mounted with longitudinally i 29is positioned within a central bearing openingr defined by the end wall-3 I'g The hubv 3E is driven from the shaft 20, as will presently be described,

yand opposite ends ofthe accumulator device. 22 are provided with rotationtransmitting connec- Vtions with the hub 33 and ther end wall 3|v of the hammer so as to form an operating connection between the motor and the hammer.

In the operation of the tool the motor may be allowed to operate continuously and actuation of .the head I3 is controlled by a disengageable connection between the hub 36 andthe shaft. 29, the operation of the disengageable connection preferably being controlled'automatically as an l,incident to the application of the head to or itswith-V drawal from the' work. To this end a control' clutch 31 is interposed between the shaft'ZIl and.

the hub 36, the clutch vcomprisingopposed teeth 38 and 39 formed respectively onthe hubland a member 40 xe'd'on the projecting end-ofthe Y shaft 20 within the casing I2. .Engagement and disengagementof the clutch 31 is effected by longitudinal shifting of the hub .36 which is in tum f .15T/@949,218 i ders.. renltmg ai separtinof the .op-"ff posed clutch elemenf suchjseparation'belng perand the shaft 2 9 to winch 'thehub 36 lsfixed'.

The clutch 31 is normally disengaged by. spring means .mountedwithin an axial bore 4I in the end of the'shaft 20 within which bore the end of the shaft`29is rotatably journaled:V Within the bore 4I ,1 the shaft 29-.has an ariialbore 42 housing an y expansive-'coil e spring 42a acting to project a' slidable. plunger 4.3 outwar`dly of the bore 42 'andv 'into contact lwitli'the'closed inner en dof the bore nctdfby iacitudinal shifting' ofthe head n' 4I The'ra'ng'e of movement f the plunger 43 is y limited by a transverse pin 44 fixed in the'shaft 23 and extending through alongitudinallyelongated slot 45 in the plunger' 43.- Thus-thespring actuatedplunger tends to;shift the Ashaft 29 outwardly ofthe .casing I2jso.as'.to open thecontrol ."clutcliV 31.v The other end 'of `the' shaft 291s A v'rotatablyjournaled'in a lbore 46in the head-I3,

ands-in its outvt'ard` shifting movement the shaftv 29 shiftsfthr head I3 outwardly in its bearing hub 23 asIimited byan'annular flan'gell1 on the -innerend. of Ythe head... l

adapted to fit about a nut or boltV head. O n the' socket 48 a tapered shank 49 of angular cross-section is formed, adapted to fit into a com-` plemental axial opening 50 in the head, and to .beheld in 'place in the head I3 by transversely slidablerlocking pins 5I mounted in the head and r engageable with 'an annular groove. 52 formed in the shank 49. To reieasably hold the pins fsa in their' active positions a sleeve 53- surrounds the head I3 within the bearing hub 23 and -when in its forward position, as illustrated in Fig. 1,

A.'I'he Vhead I3 is adaptedto receivean operating memberor tool such rasv a removable socket. 48V

the sleeve -53 forms a continuation of the inner l' When it is desired to release the socket 48 the sleeve 53 is'slipped longitudinally of the head i3 in a rearward direction to provide .clearance for4 outward shifting of the pins 5I, such shifting of .bearing surface of the hub 23 whereby to prevent outward unlocking movement of the pins 5I.

the .pins'beingefiected' by the rounded character y of ther'groove 52. To shift the sleevey 53 an outersleeve 54 slidably surrounds the hub 23 and is connected' to the sleeve 53 by pins 55 extending through-slots 56 in the hub to `engage the sleeve 53.' Asplitresilient ring 51 surrounding the sleeve 53 holds thevpins-55 in position.

To produce rapid rotative acceleration as well as rapid and complete longitudinal return movement of the hammer 2| in the reengagement of the impact clutch 25, the power accumulating.

device 22 is preferably constructed of relativelyv great .strength and is 'arranged to move the hammerZI longitudinally toward the clutch element 2B in direct proportion to the rotative move- In its preferred embodiment, the accumulator 22 is cy' mentwhich it imparts to the hammer.

lindrical, so as to surround the shaft 29 within the hammer 2|, and is formed from resilient rubber so as to yield or twist under torsional force and compress 'longitudinally when endwise force is applied thereto.

In mouldingH the accumulator 22 a plurality of rigid metallic, reinforcing rings 58 are positioned at spacedpoints intermediate the ends thereof to prevent lateral collapse of the ac'- cumulator andmaintain itin its cylindrical form as it is twisted-.", Thus, reduction of the internal diameter of thee-accumulator is prevented and binding of thershaft29 is avoided. Metallic anchor rings59'farejalso xed on the opposite ends of the accumulator in the moulding operation, theanchorrrings each being grooved at 60 in one'end surface so that'the rubber wall of the accumulator may project into the groove. By

Y copperplating and treating the rings 59 in a conventional manner, rm adherence of the rubber to the rings is insured so that substantiall torsional forces may be impressed upon the rubber of the accumulator through the medium complemental recesses 62 and 63 formed respectively in the wall 3| of the hammer 2| and in the hub 36 so as to form rotation-transmitting connections at both ends of the accumulator.

It has been found that the effectiveness of the accumulator 22 in rotating the hammer as well as in forcing the hammer 2| longitudinally is materially increased by forming the rubber wall thereof with a series of parallel ribs 64 ioined at their inner sides by a relatively thin portion 65 in which the stiiening rings 58 are moulded. The ribs 6.4 extend longitudinally of the accumulator between the anchor rings 59 and may, if desired, be normally straight 'and parallel to the central. axis of'the accumulator as in the form illustrated. The substantial spaces formed between the ribs 64 increase materially the range of the twisting movement of the accumulator whereby to permit greater momentum to be developedvin the lhammer 2|.

As the accumulator 22 is twisted so as to store i up lthe power supplied by the shaft 20, the ribs 64 assume a helical form with the grooves substantially closed as shown in Fig. 5, and'at the same time the accumulator is materially shortened to release the engagement of the hammer 2| and the impact clutch 25. Immediately thereafter the accumulator 22 unwinds, the ribs 64 assume their normal positions with a corresponding or proportional lengthening of the accumulator, and the longitudinal return movement of the clutch element 21 is in each instance fully completed before the rotative movement of the hammer brings the teeth 21 thereof into contact with the clutch teeth 26 of the head I3. The full momentum of the hammer is therefore utilized In the present tool the accumulator 22 when worn out may be readily replaced byy a new one by'removing the bolts I8 and separating the casing I2 from the gear box I6. In such separation the shaft 29 is Withdrawn from the bore 4I of the shaft 20, the spring plunger 43 being held in position in the bore 42 by its retaining pin 44. 4The shaft 29 and the hammer 2| may then be withdrawn from the casing I2, thus withdrawing the other e'nd of the shaft from its bearing in the head I3. By removing the split ring 34, the main body of the hammer 2| is released from the end wall 3|a and may be removed endwise from the shaft 29.` Thus the accumulator 22 is exposed and may be easily replaced. The engagement of the lugs of the anchor rings 59 with the recesses in the hub and the end wall 3|a is easily accomplished, and the tool may be readily reassembled by a reversal of the procedure above outlined.

In the use of the tool, the head I3 and'socket 48 are normally stationary, by reason of the normal disengagement of the control clutch 31, so as to facilitate engagement of the socket with a nut or bolt to be rotated. The body of the tool is then pressed toward the nut so as to cause shifting oi' the head I3 inwardly of the casing-I2 and thereby engage the control clutch 31.v In case the nut turns smoothly and easily as in the initial portion-of a. nut-tightening operation, the teeth.

26 and 21 remain in the position shown in Fig. 1, and the head I3 is driven directly from the motor at the same rate as the shaft 29. As the nut becomes seated,.resistance to turning increases and -the accumulator is twisted and shortened as shown in Figs. 2 and 5v of the drawings. Due to the accumulator 22 during .the prior twisting thereof. During such free movement the hub 36 is being rotated by the motor and the total rate of movement of the hammer 4materially exceeds the rate of movement of the hub 36 due to the sudden and additive action of the accumulator 22. n

In its unwinding action, the accumulatorl 22 lengthens in direct proportion to the unwinding .action so that positive reengagement of the impact clutch 25 is insured.

Since the motor is running constantly, the drivn ing force of the accumulator is coupled with or added to the momentum of the motor, and the clutch elements on the hammer will, therefore, strike the clutch elements on the head with an impact, the force of which is materially increased over that which would be obtained solely from the momentum of the motor. Moreover, the nexibility of the drive allows the motor to .operate without substantial retardation, the force thereof being stored up in the accumulator when movementv of the hammer is momentarily arrested. The operation thus described is, of course, recurrent to produce a rapid succession of blows for firmly seating the nut. The tool is then withdrawn from the work and the spring plunger 43 automatically disengagesI the control clutch 31 and stops theoperation of the accumulator and the head.

The teeth 26, 21, of the impact clutch 25 being similar in form on their opposite sides, the head I3 may be similarly operated in the opposite di` rection by reversal of the driving motor. In suchuse the tool may be used to loosen bolts or nuts, vin which use the hammering action takes place in the initial portion of the operation and is followed by direct driving of the head after the nut or bolt has been partially loosened.

It should be noted that the hammer is of much greater mass than the head and that both ham- .mer and head are compact. The head itself,

therefore, offers little resistance to movement by the impact force of the hammer and a minimum amount of the impact force is dissipated in overcoming the inertia of the head. Moreover, the compact nature of the parts minimizes the dissipation of force due to the inherent elasticity of the metal.

It will be apparent from the foregoing 'that a device has been provided which creates and utilizes an impact force much greater than can be obtained solely and directly from the motive power. Moreover, since this force is transmitted with a minimum of loss to the part being operated on, the device is highly efficient.

rthe twisting of the accumulator 22 a marked I claim as my invention: 1. A devicel for accumulating torsional force in an impact tool comprising a pair of end members, resilient means interposed between said end members and operable to resist relative rotative displacement of the end members from a normal relation, and generally longitudinal elongated resilient members extending externally on said means between said end members and acting during relative rotative movement of the end members to vary the distance between said end members in predetermined proportion to the rotative displacement thereof.

2. An vimpact tool comprising two opposed relatively movable members having releasable interengaging means constituting a driving connection between said members under certain conditions of operation, said means being successively releasable and reengageable runder other operating conditions, vand driving means for one of said members comprising a prime mover, and a power accumulator having ,an elongated body formed from rubber and operatively connected at its opposite ends .to said one of said members and vsaid prime mover respectively.

3. In an impact tool the combination of a reversible driving member, la rotatable tool head and'an operating connection therebetween comprising resilient means connected atl one end to said driving member and rotated thereby, and a separable impact clutch having one clutch element on said head and the. other element connected to said resilient means, said clutch elements having rotation transmitting cam faces similarly operable in either direction of rotation of the driving member to eiect rela tive'separation of said elements when rotation of said head by said member is resisted by a predetermined force. y,

l4. A tool of the character described comprising a driving member and a coaxial tool head, means supporting said tool head for rotative and longitudinal movement, a hammer mounted for rotative and longitudinal movement between and coaxially with said head and driving member, a releasableimpact clutch between said hammer and said head, a resilient power accumulator having one end connected to said hammer for rotating and axially moving the hammer to operatively engage said impact clutch, a normally open control clutch having one element fixed to said driving' member and an opposed element drivingly connected to the other end of said accumulator, and means operated by'axial movement of said tool head asA it is engaged with the work to engagey the ele- `ments of said control clutch.

5. An impact tool comprising a driving member, a tool head` mounted'for axial and rotative movement, a rotatable' hammer, a disengageable impact clutch interposedV between said hammer and-said head for transmitting rotative forces therebetween, said clutch having engageable l .,trol clutch having one element'connected-to said driving member and the other element connected to the other end of said accumulator, and

"-means actuated by engagement of thel toolhead g with 4the work to operate said control clutcln 6. An impact tool comprising a rotative driv- V ing member, an alined tool head mounted for rotation and limited axial movement, a shaft extending between and having its opposite ends rotatably journaled in said driving member and said head, a cylindrical hammer surrounding said shaft and having a rotative and slidable engagement with said shaft at one end, an impact clutchat said end of the hammer having axially separable elements on said hammer and head respectively, a hub mounted on said shaft for longitudinal movement therewith and forming a rotative and slidable bearing for the other end of said hammer, a power accumulating device within said hammer having its opposite ends connected to said hammer and said hub, a control yclutch having opposed separable elements on said hub and said driving member, and means acting to maintain said clutch normally open, said clutch being adapted to be closed by axial shifting of said head, said shaft and said hub in the application of the tool to 20 the work. 1

7. An impacttool comprising a rotative drive ing member, an alined tool head mounted for rotation, a shaft extending between and having its opposite ends rotatably journaled in said driving member and said head, a cylindrical hammer surrounding said shaft and having a rotative and slidable engagement with said shaft at one end, an impact clutch at said end of the hammer having axially separable elements on said hammer and headV respectively, -a hub mounted on said shaft for longitudinal movement therewith and forming a rotative and slidable bearing for the other end of said hammer, and a power accumulating device within said hammer forming a rotation-transmitting con- 3 tool head'rotatably andslidably mounted in the` other vend of said casing' and having a clutch element thereon,v and a hammer assembly re-` movablefrorn said casing as a unit when theV casing is detached from said housing, said hammer assembly comprising a central shaftr rotatably and slidably journaled at its opposite ends `in said head and said Vdriving member when said casing and housing are in assembled relation, a cylindrical hammer surrounding said shaft and having a rotatable and slidable bearing engagement with said shaft at one end, a hub fixed to said shaft, an end wall detachably fixed to said hammer and having arotatable and sliding bearing engagement with said hub, said hub having a'flange Within said hammer and engageablewith said end wall, a power accumulator within said hammer having rotationtransmitting Aconnections at its -opposite ends with said hammer and said hub, and said hub and said-hammer having clutch elements thereon engageable -with .the clutch elements on said driving member and Vsaid head,.the elements on said head andzsaid'fhammer having a camV engagement tending ,to disengage said element when a predetermined force opposes rotationof.

said head. y

9. A power transmitting device for the accumulation of energy from-a driving member and the delivery of accumulated energy to a driven memf,

ber with an impact force comprising a body formed from resilient rubber, and axially facing means on the opposite end faces oi said body to be engaged for the application of torsional stress to said body.

10. A power transmitting device for an impact tool comprising, in combination, a resilient bodyV capable of being rotatably twisted with like effeet in either direction out of a normal condition, means at one end of said body through which a power irnput Vmay be applied to twist said body and thereby effect a'n accumulation of energy therein, and means at the other end of said body through which a driving connection with a part to be driven may be established and released accumulated energy transmitted to the driven part.

11. For use in an impact tool, a power transmitting device comprising, in combination, a rubber body capable of accumulating energy when a torsional force is applied thereto, means for connecting one end of said body with a rotatable prime mover, and means at the other end of said body for transmitting the accumulated energy of the body by rotational impact to a part to be driven. i

12. For use in an impact tool, a force accumulator of the character described comprising an elongated resilient body having means at its opposite ends by which said ends may be relatively rotated to accumulate torsional energy in said body, said body having generally longitudinally extending external means for determining the proportion between the extent of said relative rotation andthe variation of body length caused thereby.

13. A power accumulating device adapted for use in an impact tool recurrently to store up enei'gy de rived from a prime mover and to expend such stored energy in the form of an impact upon a working member, comprising an elongated member formed of resilient rubber, and means for connecting said member operatively in an impact tool, said member having generally longitudinal external alternating ribs and. grooves thereon of predetermined dimensions producing when the device responds to a torsional force a correlation of the relationship between the extent of diminution of length and-degree of response as torsional force is applied to one end of the device while the other end is relatively held against rotation.

14. For use in an impact tool or the like having a prime mover, work performing means, and an interruptable driving connection therebetween including rotatable parts separable by relative axial movement, a power accumulator for effecting such movement and return', comprising an elongated member resiliently yieldable longitudinally and rotatably and having means for correlating the extent to which the length of said member is diminished as relative rotation of its ends occurs under the imposition of a torsional force so that separation of said parts is effected upon a predetermined degree of such relative rotation.

l5. A power accumulating device for an impact tool having a disengageable clutch mechanism including a driven partcomprising an elongated member of resilientrubber-like material adapted to be interposed between a prime mover and said driven part as the sole driving connection, said member being dimensioned to become substantially shorter as a torsional force tending tool of the character described comprising a resilient rubber member 'of mass ample to provide rigidity in said member for transmitting a rotary driving force yet yielding throughout the major portion of its length for the accumulation of energy upon the imposition of such rotaryy driving force when one end of the member'is momentarily held again rotation, and 4end face means for connecting said member with driving and driven elements of an impact tool.

17. A power accumulating device for'an impact tool of the character described comprising an elongated hollow member of resilient rubber having walls of ample thickness and mass to transmit a rotary driving force for operating an impact tool under onel load condition and resiliently yieldingto acquire torsional energy Vwhen a heavier load condition prevents the transmission of said driving force by restraining movement of one end of said member and to expend such acquired energy when the restraint is removed, and means for connecting said membero with a free axial movement in an impact tool.

18. A power accumulating device for an impact tool comprising, in combination, a member of resilient rubber having a bore therethrough to receive a driving element of the tool, means on one end face of said member for connecting said member with said driving element, and means on the other end of said member for connecting it with a driven element of said tool.

19. A power accumulating device for an impact tool comprising, in combination, a cylindrical member of resilient rubber having an axial opening through which a driving element of the tool may extend, means at one end of said member aiording an axially detachable intertting drive connection with said driving element, and means at the other end of said member aiording a freely detachable connection with atool element to be driven.

20. In an'impact tool, the combination of a reversible driving member, a rotatable tool head and an operating connection therebetween comprising resilient means connected at one end to said driving member and rotated thereby and a separable impact clutch having one clutch element connected with said head and the other clutch element connected with said resilient means, said limpact clutch including rotation transmitting 'automatically reestablish it after release, a prime mover, and a resilient driving connection between said driving member and said prime mover and constituting the sole driving connection therebetween, said resilient driving connection being adapted to be placed under torsional stress when Ymovement of the driving member in-either direction is opposed and concurrently therewith to be shortened to permit release of the driving connection between said driving and driven members followed by an acceleration of the driving member by release of the torsional stress to re- 1 I i l engage said vfirst mentioned driving connection. 22. A rotary impact tool having an elongated -casing, a rotary drive member projecting into said casing, a power accumulating unit :in said casing and comprising an elongated body of resilient material` adapted to be placed under internal tension and to accumulate torsional energy when twisted in either direction out of a normal position, and to return to said position connection with said unit.

ROBERT H. POTI'. 

